Volume 80, Issue 1

In recent years, the metal processing industry has undergone a massive rethinking in terms of energy use. With the phase-out of nuclear energy, Germany wants to take responsibility and embark on a more sustainable path to green electricity. Not only due to the discontinuation of fast-available nuclear energy, but also due to the increasing demand for electrical energy and the geopolitical situation, the costs for production are continuously rising. Furthermore, the use of fossil fuels has come under criticism in the face of current climate policy discussions, and the procurement of fossil fuels such as natural gas has experienced a significant price increase due to the current geopolitical situation. A more efficient use of energy and resources is therefore essential, also with regard to socio- and environmental factors and, in particular, climatic aspects. In this work, a standard industrial gas nitriding process is examined with regard to its key energy figures and potential savings are identified. On the basis of these, the significance of the heating of the components, the insulation technology and other process-relevant energy flows is determined. It was found that, on the basis of conservative calculation models, the heating of these industrial furnaces types is among the largest energy consumers, whereas only a smaller part is required for treating the components. Furthermore, the majority of the electrical power provided dissipates as power loss from the heat treatment process.

Additive manufacturing of metals by electron beam-based powder bed fusion (PBF-EB/M) is widely used for processing of numerous alloy systems. However, up to now there have been only a few studies investigating tool steels using PBF-EB/M. Due to high build chamber temperatures during processing, PBF-EB/M provides advantages for such steels. These conditions, for example, help to avoid cracks. In the present study, the high-speed steel (HSS) Böhler S390 Microclean (similar to M42, 1.3247) has been processed using PBF-EB/M. As a first step, two different parameter sets, i. e., two different resulting line energies and their effect on the resulting network-like cell structure, were investigated. Nanoindentation measurements revealed strong differences in hardness and elastic modulus between the network-like cell structures and the martensitic matrix, which could be attributed to the formation of carbides during solidification, which were probed by scanning electron microscopy. In addition, monotonic tensile properties were characterized on specimens built with a parameter set adapted to the geometry in order to consider one of the most critical loading scenarios for the tool steel in focus. The investigations reveal a high tensile strength with relatively low elongation at fracture.

To enhance patient care, it is necessary to increase the lifetime of double modular hip endoprostheses with tapered junctions. One approach to increasing the lifetime of components is to adjust the residual stress state to the load. Therefore, this study investigates the influence of process parameters and the effect of their interaction on the residual stresses of neck adapters manufactured from CoCr28Mo6. With the investigated process parameters, compressive residual stresses are present after turning. This study reveals the interaction and issues between surface roughness and the high bending of the surface due to the small radius of the samples in the measurement of residual stress.